Title

Author

Document Type

Thesis - University Access Only

Award Date

2013

Degree Name

Master of Science (MS)

Department

Agricultural and Biosystems Engineering

First Advisor

Kasiviswanathan Muthukumarappan

Abstract

The need for new ethanol coproduct markets grows as the industry expands. Currently, process streams such as thin stillage (TS) and condensed distillers solubles (CDS) are processed into distillers dried grains with solubles (DDGS) which are used primarily as a feed ingredient, but there may be other valuable uses for them. This study identified properties of the upstream components, TS and CDS, to determine potential value and determined the possibility of utilizing the energy density of DDGS through pyrolysis. Chemical analysis of TS and CDS identified zein and glycerol. The physical properties of the TS and CDS gave insight about processing and storage requirements, which are important for developing value extraction methods. Both materials had high moisture contents making them susceptible to spoilage and indicating that they behave similarly to water in terms of flow and heat transfer. Pyrolysis was used to produce biooil and bio-char from DDGS and other ethanol coproducts. It was determined that the slow pyrolysis produced bio-oil comparable to bio-oils produced from other biomaterials (wood, rice husk, big blue stem, prairie cordgrass, corn stover, pine bark and needles, and more), but the DDGS based bio-oils was less acidic. The presence of tar in the bio-oils caused the density to be greater than one and the viscosity to behave as a shear thinning liquid. The lower heating values for the bio-oil were less than the heating values of commonly used fuels, yet comparable to the heating values of other pyrolysis bio-oils. Once new markets for the coproducts are found, the processing required to meet the needs of the markets must be efficient and inexpensive in order to be economically feasible. Computer simulation programs like SuperPro Designer allow for mass and economic balances of individual unit operations and entire processes to be made. In addition to exploring new value added products, this study used computer simulation to evaluate DDGS fractionation. It determined that coproducts are an essential component to the sustainability of an ethanol plant in that: 1) they have continued marketability to the livestock industry, and 2) processing is not overly-expensive.